The invention discloses an oil spill prevention device of an oil-electric hybrid unmanned aerial vehicle. The device comprises an oil tank, the left side of the top of the oil tank communicates with arefueling pipe, the right side of the oil tank is fixedly connected with an auxiliary oil tank, the right side of the auxiliary oil tank is fixedly connected with a transparent observation window, the top of the right side of the oil tank communicates with an oil overflow pipe, and the end, away from the oil tank, of the oil overflow pipe penetrates the auxiliary oil tank and extends into the auxiliary oil tank. The invention relates to the technical field of unmanned aerial vehicles. According to the oil spill prevention device of the oil-electric hybrid unmanned aerial vehicle, in the refueling process, overflowed fuel oil enters the auxiliary oil tank, an operator stops refueling when seeing that the fuel oil reaches the auxiliary oil tank through the transparent observation window; inaddition, the capacity of the auxiliary oil tank is reasonably designed according to the reaction time of general personnel and the expansion coefficient of liquid under the natural temperature difference, the use requirement is met, a handle is pulled up and down, a sponge wiper can be driven to move up and down, the transparent observation window is wiped clean, oil contamination is prevented from influencing judgment of operators, and reliability is improved.